1. Field of the Invention
The present invention relates to a power-up initial circuit, and particularly to a power-up initial circuit that not only can increase a power-up capability, but can also reduce a side effect or a latch-up effect not wanted by a user.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating a power-up initial circuit 100 according to the prior art. When a high voltage start-up signal VHES does not start up a high voltage generator 102, the power-up initial circuit 100 utilizes an N-type metal-oxide-semiconductor transistor 104 to fix a voltage of a node A at a voltage VCC-Vth, where VCC is an internal supply voltage, Vth is a threshold voltage of the N-type metal-oxide-semiconductor transistor 104, and the high voltage start-up signal VHES is generated by a power-up circuit. When the high voltage start-up signal VHES stars up the high voltage generator 102, the high voltage generator 102 generates an internal high voltage VIH, where the internal high voltage VIH is higher than the voltage VCC-Vth.
In an advanced metal-oxide-semiconductor transistor process, the internal supply voltage VCC is gradually reduced with an advance of the metal-oxide-semiconductor transistor process, so the voltage VCC-Vth is also gradually reduced. Because the voltage VCC-Vth is gradually reduced, a power-up capability of the power-up initial circuit 100 is reduced, and the power-up initial circuit 100 may exhibit a side effect or a latch-up effect not wanted by a user. Therefore, the power-up initial circuit 100 is not a good power-up initial circuit for the user.